Temperature-sensitive bulb



May 19, 1925. v

v F. J. BAST TEMPERATURE SENSITIVE BULB- Fi1 ed Jan. 3, was

, avwentoz fjwfd, 22M

Patented May 19, 1925.

'UNITED STATES 1,538,610 PATENT OFFICE.

FRANK J. .BAST, OF BROOKLYN, NEW YORK, ASSIGNOR TO CHARLES J. TAGLIABUE MFG. ('20., OF BROOKLYN, NEW YORK, A CORPORATION OF NEW YORK.

TEMPERATURE-SENSITIVE BULB.

Application filed January 8, 1923. Serial ljIo. 610 ,581.

To all whom it may concern:

-Be it known that I, FRANK. J. BAs'r, a citizen of the United States. and a resident of the borough of Brooklyn, county of Kings, city and State of New York. have invented a certain new and useful Improvement in Temperature-Sensitive Bulbs, of which the following is a specification.

My invention relates to temperature sensitive bulbs of the type commonly found in sensitive systems of a mercury filled recording or dial thermometer or thermostat and generally including an expanding-contracting member such as a spiral, helical or Bourdon tube and the like whereby certain definite movements in response to temperature changes are obtained. In practice it is required to fill such systems with mercury under considerable pressure, which in use is increased to a still further internal pressure becauseof expansion resulting from exposure of the bulb portion to higher temperatures. Because of such high pressures joints of the type commonly referred to as mechanical joints are wholly unsatisfactory,

due to the development of leakage as a result of the high pressures exerted upon said joints. Heretofore taper plugs and screw plugs have been tried without success for closing the ends of the bulb-chamber and have even been welded in place without, however, providing leak-proof closures for any appreciable periods of time. The object of the present invention is to provide a bulb of novel and simple construction in which these objections and disadvantages are overcome and whereby an absolutely leak-proof structure under all pressures is produced. Other more specific objects of the invention will appear from the description hereinafter and the features of novelty will be pointed out in the appended claims.

In the accompanying drawings, which illustrate an example of the invention without defining its limits, Figs. 1, 2, 3 and 4 are diagrammatic views illustrating successive steps in the method, Fig. 5 is an elevation, partly in section, showing the bulb prior to its final stage and Fig. 6 is an elevation illustrating the finished bulb.

In carrying out the novel method whereby the bulb may be produced, a solid piece of metal, preferably in the form of a cyllndrical rod and of the proper dimensions is machined or otherwise fashioned to produce the bulb member 10 shown in Fig. 1 and having an interior chamber 11 enlarged at one end to form an annular flange 12. At its other end the member 10 is preferably reduced in diameter and provided with an interior passage 13 communicating with the chamber 11 and with two adjacent recesses 14 and 15 which-terminate in the end face of said member 10.

The latter, in the condition illustrated in Fig. 1, is then placed in a die 16 which is mounted in a suitable die-holder and secured, for instance, to the anvil of a drop-hammer in registry with a die 17 fixed, to the hammer portion of said drop-hammer, it being understood that the die 17 is properly shaped as indicated at 18 to perform its functions as will be described more fully hereinafter. As shown in Fig.2 the flanged end of the member 10 projects-beyond the die 16 and through a spacing washer 19 of predetermined thickness which is placed over said projecting end so as to rest upon the die 16. At this stage the hammer with its die 17 is temporarily fixed in a raised position at a distance above the washer 19 and that portion of the member 10 which extends above the same is heated, for instance by means of an. acetylene torch flame until it is brought to a white heat. While the projecting end is in this condition of white heat the hammer is raised and permitted to drop to bring the die 17 to the position shown in Fig. 3. The action of the die 17 upon the heated end of the member 10 turns the flange 12 inwardly as indicated in Fig. 3; because of the presence of the washer 19 the drop of the hammer is arrested at such a point that the flange 12' is only partly turned in as indicated at 20 so that, at this stage, the end of the bulb chamber 11 is only partly closed.

The hammer is now. again raised and fixed at a distance above the anvil after which the washer 19 is removed. The projecting end of the member 10 is then again brought to a white heat, for instance b means of the flame of said acetylene'torc after which the hammer is again dropped to bring the die 17 to the position shown in Fig. 4:. Because of the removal of the washer 19 the die 17, at this stage, has anadditional drop suflicient to turn the flange 12 completely inward as indicated at 20 with the result that this end of the chamber 12 is welded shut as shown in Fig. 5. As

I preferably also by welding. The short tube the neiit step the bulb is cleaned n V for instance in a lathe and finished as s own in Fig. 6. I

One end of a capillary connecting tube 21 is then inserted into the recess 14 and .welded' therein and a short length 22 of capillary tubing is also inserted into the recess 15 and welded therein; the opposite end of said tube 21 is joined to the co-opcrating expanding-contracting member 23 lent in said system under a predetermined pressure. after which said tube 22 is lightly pinched together, close to the bulb 10 for instance in a suitable vise. While held in this manner, the end of said tube 22 is disconnected from the pump and welded shut after which the vise is removed. The described method of producing the bulb 10, filling the system with mercury and'sealing the tube 22,- results in a temperature sensitive system in which all connections and openings are welded closed even though the filling is under high pressure.

To recapitulate, the flanged end of the bulb 10 is closed by welding, intwo succes sive steps rior t0 and between which the end of sai bulb is brought to a white heat so as to be capable of being efiiciently welded: the capillary tube is connected with said bulb by weldin and after the mercury has been introduced and placed under pressure,

.perature increases to whic 'vention lendsitself to any type of tempiraat end of the filling tube is also closed by 0 being welded.

A bulb and temperature sensitive system of maximum efiic iency is thus produced in an economical and simple manner, and the possibility of leakage, even under the higher internal pressures develo ed during tem- Ethe bulb may be subjected, is practically obviated. The inture sensitive system in which de ite movements are obtained in response to .temperature variations.

Various changes in the specific forms shown and described may be made within the scope of the claims without departing from the spirit of the invention.

I claim:

1. A unit for use in inaking temperature sensitive bulbs comprising a member having an internal ,chamber, an annular shoulder at one end of said chamber and a flange on said member projecting from said shoulder and ada ted to be turned inwardly thereon find wel ed to close one end of said cham- 2. A temperature sensitive bulb comprising a mem )er having an iiiternal chamber and a flange at one end of said member extendin inwardly to a common point and welde at said common point tohclose one end ofsaid chamber, said member'being provided at its opposite end with a recess for the reception of a capillary tube and with another recess for the accommodation of a.filling tube,

-In testimony whereof I have hereunto set my hand.

FRANK J. BAST. 

